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Gridded Data Format

Please be advised! Once you click on the particular gridded file you wish to obtain, it will open an anonymous ftp session where you can download the file. The gridded files are gzipped because of their size. When they are unzipped, each file is about 3 megabytes in size. Users may feel free to utilize a viewer that can translate the downloaded uncompressed gridded file format into a comma-delimited ascii version: http://storm.aoml.noaa.gov/hwind/gridded/

Below is a description on how the read the file.

The gridded files of cyclone wind components have the following structure:

  1. A few lines giving the grid spacing in meters and the latitude and longitude of the storm center. In mercator cartesian coordinates the storm center is at (x,y)=(0,0)

  2. Cartesian coordinates (meters) are then given for the grid boundaries. First listed are the WEST TO EAST mercator X coordinates which pass through the storm center at x=0. They are listed in increasing order from WEST to EAST. The total number of entries is given before the coordinate listing so that the entire set of MERCATOR X COORDINATES can be read in at once.
  3. Next the SOUTH TO NORTH mercator Y coordinates (meters) which pass through the storm center at y=0 are listed. They are listed in increasing order from SOUTH to NORTH. The total number of entries is given before the coordinate listing so that the entire set of MERCATOR Y COORDINATES can be read in at once.

  4. The next listing is the EAST LONGITUDE COORDINATES of the grid boundary followed by a listing of the NORTH LATITUDE COORDINATES of the other two grid boundaries. Again, before the actual coordinates are listed. an integer specifying how many coordinate entries follow is given to facilitate reading them in as a single array all at once.
  5. Finally, the SURFACE WIND COMPONENTS (M/S) are listed as a listing of complex numbers of the form (u,v). They should be read in as a SINGLE COMPLEX ARRAY of two dimensions. The dimensions of the array are given on a line preceeding the actual component listing again so that the entire array can be read in at once.


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